Mailpiece sorting can be performed manually or with automated equipment designed specifically to perform the sorting task. Manual sorting is labor intensive and time consuming and has historically been done using pigeon hole type sorting stations. Typical modern mailpiece sorting equipment incorporates a feeding mechanism for feeding mailpieces, a separating mechanism for separating the mailpieces from each other, a reading means for reading the information on the mailpieces, a mailpiece transport mechanism for transporting the mailpieces to compartments or bins, compartments or bins for receiving the mailpieces, and software for making choices regarding placement of mailpieces into the compartments and a control device.
The operation of automated sorting equipment typically entails an operator placing an armload of mail that has been edge aligned onto the feeder portion of the apparatus. The mailpieces are fed into the sorting apparatus and sorted into bins or compartments. Typically, when one or more bins become full, the sorting apparatus stops, and the bins are manually emptied into a mail tray by an operator. The foregoing increases the amount of time that is required to sort the mail. Some apparatus have complex automated mechanisms for emptying bins. From the mail tray, the mailpieces are either sent to a delivery location or sorted again. After the full bin(s) have been emptied, if additional mailpiece sorting is needed, the sorting apparatus is restarted and sorting continues.
The stopping of the sorting apparatus for full bins is typically performed with the assistance of bin-full sensors. The typical mail sorting apparatus has two sensors in each bin. The first sensor senses when the bin is almost full. The amount in the bin when it is almost full is the minimum amount that is acceptable for storage in a postal service mail tray. The second sensor senses when the bin is full. The amount in the bin is the maximum amount that can be stored in a postal service mail tray.
Another type of sorting apparatus disclosed by the prior art utilizes a cartridge, inserted into the bin, for collecting the mail. The cartridge is removed from the sorting apparatus by use of a robotic apparatus which transfers the cartridge to a docking station. This system requires stopping of the sorting apparatus each time a bin is full.
All of the above mentioned sorting systems require stopping of the sorting apparatus to clear the bins. Stopping the sorting apparatus decreases the efficiency of the sorting machine since the machine is not operating when it is being emptied. Other sorting systems deal with full bins differently as explained below.
Sorting apparatus that have two arrays of bins are also used. The mailpieces are first sorted into a first array of bins and, while those bins are being swept or emptied, the mailpieces are resorted into a second array of bins. Thus, the down time of the sorting machine is reduced by having a second path that can process mailpieces while the first path is shut down. The second sorting path makes the system complex, less compact and adds to the cost of the system.
Still, other sorting apparatus use a first set of bins which are configured to eject mail into a second set of bins which convey below the first set of bins. In this arrangement, when a bin is full, the mailpieces can be ejected without stopping the sorting apparatus. However, this arrangement is mechanically complex and requires many moving parts and coordination of the second set of bins, called conveying bins, with the ejection of the mail from the first set of bins.
Thus, one of the problems of the prior art is that some systems shut down frequently for full bins to be emptied. An additional problem of the prior art is that some systems require two bin sensors per bin to sense the fullness of the bin. Another problem of the prior art is that the sorting time is not maximized. Another problem of the prior art is that multiple bin sets are required for some systems. Yet another problem of the prior art is that some of the sorting bins require an ejection shoot, and the multiple bin sets require timing between bins for catching ejected mail. Yet another problem of the prior art is that some of the sorting bins require additional apparatus such as a cartridge in the bin for capturing and removing the mailpieces.